Business

RXR buys 340 Madison for $570 million

The office building at 340 Madison Ave. is expected to be sold to RXR Realty for about $570 million, $20 million more than the sellers paid for it in 2006 when it was 40 percent leased.

Sources told The Post that a contract is to be signed on the 750,000 square foot building, which is now 92 percent leased, this week. Social-networking giant Facebook is among the building’s tenants.

According to sources familiar with the transaction, to win the deal over rival bidder USAA, RXR agreed to pay cash now for a partial stake and then replace the current, unassumable financing, which carries a low interest rate, with a new mortgage in the next year or so. The deal is equal to $760 per square foot.

The deal would be a first for RXR, a Uniondale, LI-based firm led by Scott Rechler that emerged after the buyout of Rexson Associates Realty, the family’s real estate investment trust.

Marketing on the property was done by Darcy Stacom and Bill Shanahan of CB Richard Ellis.

The brokers, RXR and current building owner Broadway Partners all declined to comment.

Broadway, which is run by Scott Lawlor, purchased the building from Macklowe Properties for $550 million. Macklowe had reinvented the older structure into a modern, high-tech office tower before losing most of its properties in the real estate downturn.